To those who have read the preceding chapters--particularly those relating to shipping and all other classes of transportation--it will be clear that this constitutes an international as well as a national problem. The course of events in connection with the world industry may even be said to have a paradoxical aspect. American petroleum became an international institution when, shortly after the Pennsylvania discoveries, the eagerness of other nations to secure it was evinced. The increase of production was so rapid that for years the supply far exceeded the domestic demand, and made the creation of foreign markets necessary to the American oil interests. These foreign markets have contributed materially to American national wealth and are now an important factor in the country’s favourable trade balance; exports of petroleum products from the United States for the year 1919 representing a value of $343,776,385, and ranking fourth in order of importance of the country’s exports. Our oil companies have been international traders for several decades, but their operations have been entirely based on private initiative and have rarely benefitted by official coöperation. The phenomenal growth of inventions and manufactures pivoting on the products of petroleum, which has transpired during the twentieth century, has, however, entirely reversed the situation that existed in the year 1900. Though the United States provides almost seventy per cent. of the world’s production from wells on her own soil, she is to-day actually an importer of crude oil to meet the needs of the domestic market, combined with those of the foreign market for the manufactured products of petroleum, which yield vast revenues to American wage-earners engaged in their creation.